RE: [PATCH] [extcon]:remove freed groups caused the panic or warning in unregister flow

[Wang, Xiaoming]

Dear Choi

-----Original Message-----
From: Chanwoo Choi [mailto:cw00.c...@samsung.com] 
Sent: Monday, November 04, 2013 9:43 AM
To: Wang, Xiaoming
Cc: myungjoo....@samsung.com; linux-kernel@vger.kernel.org; Liu, Chuansheng; 
Zhang, Dongxing
Subject: Re: [PATCH] [extcon]:remove freed groups caused the panic or warning 
in unregister flow

Hi Wang,

>  drivers/extcon/extcon-class.c |    3 ++-
>  1 files changed, 2 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/extcon/extcon-class.c 
> b/drivers/extcon/extcon-class.c index 148382f..48f4669 100644
> --- a/drivers/extcon/extcon-class.c
> +++ b/drivers/extcon/extcon-class.c
> @@ -794,6 +794,8 @@ void extcon_dev_unregister(struct extcon_dev *edev)
>               return;
>       }
>  
> +     device_unregister(edev->dev);
> +
>       if (edev->mutually_exclusive && edev->max_supported) {
>               for (index = 0; edev->mutually_exclusive[index];
>                               index++)
> @@ -814,7 +816,6 @@ void extcon_dev_unregister(struct extcon_dev *edev)
>       if (switch_class)
>               class_compat_remove_link(switch_class, edev->dev, NULL);  #endif
> -     device_unregister(edev->dev);
>       put_device(edev->dev);
>  }
>  EXPORT_SYMBOL_GPL(extcon_dev_unregister);
> 

I think we could only apply following patch instead of moving the position of 
device_unregister().

diff --git a/drivers/extcon/extcon-class.c b/drivers/extcon/extcon-class.c 
index 148382f..ff27b19 100644
--- a/drivers/extcon/extcon-class.c
+++ b/drivers/extcon/extcon-class.c
@@ -805,10 +805,8 @@ void extcon_dev_unregister(struct extcon_dev *edev)
        for (index = 0; index < edev->max_supported; index++)
                kfree(edev->cables[index].attr_g.name);
 
-       if (edev->max_supported) {
-               kfree(edev->extcon_dev_type.groups);
+       if (edev->max_supported)
                kfree(edev->cables);
-       }
 
 #if defined(CONFIG_ANDROID)
        if (switch_class)

Thanks,
Chanwoo Choi

        I don't agree with you.
        Why do not you want moving the position of device_unregister()?
        It will cause the memory leak if has not kfree 
edev->extcon_dev_type.groups as your patch do firstly. And if you think kfree 
edev->extcon_dev_type.groups is meaningless well then kfree 
edev->extcon_dev_type.groups in function exton_dev_register (line 756)also 
should be removed I think. What do you think?

Thanks
Xiaoming.